Excessive sun exposure is extremely dangerous. For example, too much sun exposure can cause painful sunburn, immune system suppression, skin rashes, premature aging of the skin and skin cancer. Yet even with modern understanding of the harmful effects of sun exposure, most people still do not protect themselves adequately from the sun.
During the summer a small percentage of the population may think to apply sunscreen if they know they will be spending significant time outdoors. However, most of these people will not apply sunscreen if they think they are going to be indoors or in a covered area, such as their automobile.